Unable to install pxctest via brew as doesn't build on OS X 11.6 using Xcode 8.2

[samhann]

Installation fails with the following log

==> Installing pxctest from plu/pxctest
==> Cloning https://github.com/plu/pxctest.git
Updating /Users/samhan/Library/Caches/Homebrew/pxctest--git
==> Checking out tag 0.3.1
==> ./scripts/build.sh /usr/local/Cellar/pxctest/0.3.1/libexec
Last 15 lines from /Users/samhan/Library/Logs/Homebrew/pxctest/01.build.sh:
2017-02-03 12:05:29 +0530

./scripts/build.sh
/usr/local/Cellar/pxctest/0.3.1/libexec

/private/tmp/pxctest-20170203-2407-4xnvuf/Dependencies/Commander /private/tmp/pxctest-20170203-2407-4xnvuf
Cloning https://github.com/kylef/Spectre.git
git: The build tool has reset ENV; --env=std required.
swift-package: error: No version tag found in (/private/tmp/pxctest-20170203-2407-4xnvuf/Dependencies/Commander/Packages/Spectre.git) package. Add a version tag with "git tag" command. Example: "git tag 0.1.0"

READ THIS: https://git.io/brew-troubleshooting
If reporting this issue please do so at (not Homebrew/brew):
  https://github.com/plu/homebrew-pxctest/issues

[plu]

Can you please try to update Homebrew? Issue #5 had the same error message and an update of Homebrew fixed it.